Art of producing pigments by electrolysis.



E. D. CHAPLIN. ART OF PRODUCING PIGMENTS BY ELEGTROLYSIS.

APPLICATION FILED FEB. 3, 1906.

. b06402. Patented VVI'TNESEEE: I I INVE T I wg mmJ M @MW UNIT-ED STATES PATENT YQFFICE;

iEDWlN D. oHA'PLni, ornos'rou, IVIASSAOHUSETTS, ssrenon roirhRNATIoNAL LEAD 1 COMPANIES, A. VOLUNTARYASSOCIATION.

AR'r or rnonuomenrerrnnrrs BY E LEo'rnonvsis.

Specification offL e ttem Patent.

P'atented'Dee. e, 1908 Application filed February 3, 1 9 06. Serial 1N0. 299,235.

'To (ill whom 'it may concern: Be it knownthat I, EDWIN DgCHAPLIN, a citizen ofthe United States, and a resident of Boston, in thecounty of Suffolk and "State --of Massa'chusetts, have invented anewand useful Improvement in the Art of-Produeing Pigmentsby Electrolysis, of which the 'fol lowing is a specification.

My inventionrelates to the art of producing 10 pigments-by electrolysis and it relates more particularly to a .process for. so producing white. lead or lead carbonate.

In the ..manufacture of lead carbonate by electrolysis, I prefer to employ an electrolyte 15, which under the influence of the electr'iccurrent will separateinto a-so'lvent of lead and an alkaline hydrate. and thereby'to produce in the anode compartment containing metallic lead, which may be the anodeiof the electrolyzer', a-solution of a soluble salt of lead,

and" in the cathode compartment, an alkaline hydrate" have fo'u'ndit essential to the commereial'production of white lead to mainabove briefly set forth, is described in United.

States Letters Patent No. 563,553, dated 7 July 7, 1896, granted to A. B. Browne and B5 myself, and according to said process the. aforesaid soluble salt of lead. is precipitated by the aforesaid alkaline hydrate to produce lead hydrate, and-saidlead hydrate -is then carbonated-in any suitable manner.

7 40 -The object of the.}present invention is to' provide} a direct process" of electrolytically reducing white lead, or one wherein the solu- Ele salt of lead isdirectly carbonated without first precipitating lead hydrate. therefrom. I have dlscovered that the products o b' tained by the indirect process described in the aforesaid patent and by the direct rocess described in the present application iffer in 'molecular structure,- and that for some purposes one'product, and for other purposes the other product, is preferred by painters.

-My'invention may best be understood'lnz having reference to the drawing which-ac companies and forms a part of this specifics tion, and whichillustrates in diagrammatic form one arrangement of apparatus and circuitswhereby my process may be carried into eflect;but.it 'is to'be understood that my process is broader than mere apparatus, 7

and may be carried into effect by a great varietyof apparatus and circuit arrangements. In the drawing, the figure represents an apparatus and system of circuits for electrolytic'ally producing white lead.

In the figure, 1 represents a supply tank containing an'electrolyte which, under the influence of the electric current, will be separated into a' solvent of lead'and an alkaline hydrate. 'I prefer to employ as an electrolyte, an aqueous solution of a non-alkaline salt such as a nitrate or an acetate of an al kaline' base, for example sodium nitrate.

3 represents an electrolyzer divided into an anode compartment 3 and a cathode compartment 3", by means of the foraminous .diaphragms 4.4, between whichi-s formed a compartment for receiving the electrolyte from the tankl through the pi e 2, which is providedwith a valve 2. For t e purpose-of preventing a .mixture of the anolyte and catholyte in the electrolyzer and consequently a preci itationof lead hydra e in the electrolyzer, may maintain a preponderance of pressure on the inner sides of said diaphragms,

preferably by maintaining the level of the electrolyte between the diaphragms higher than the level of the anolyte and catholyte. The level of the electrolyte in the compartment between the diaphragms is indicated by the dottedline 9, and the level of the anolyte.

and catholyte, 1 which is governed bythe I height of the bends of-the outlet pipes 7 a'pd .n.

8, is indicated by the dotted lines 10, 1 0. order to prevent saidoutletpipes from s1- phoning the liquids out of the electrolyzer, the upper portion of each of said bends may be provided with an opening 26, 26 to equalize the atmospheric pressure on the columns of liquid in the two portions of each of said pipes. ,D The lead to be operated upon-is placed in the anode compartment and may form the anode oftbe electrolyzer. 1in. the resent case the lead is shown in the form o a lead pig 5, connected. by the conductor d.,to the positive pole of'tli'e dynamo D, or other suit able source'of current. 'lhe'cati1ode'of the ier.

tank. 15.

other suitable metal, and is connected by the conductor 0 to the negative pole of the dynamo.

'hen the valve 2- is opened and the electrolyzer is charged with a suitable electrolyte from the supply tank 1 ,the current from the source D is passed through said electro-' lyte and decomposes the same into a solvent of lead and an alkaline hydrate. The lead is dissolved by its solvent, producing thereby a solution of a soluble salt of lead in the anode compartment 3, which solution is drawn offby means of the pipe 8 into the precipitating The alkaline hydrate is drawn off by the pipe '7 into thetank 11, where it may be converted into an alkaline carbonate-by subjecting it to the action of carbon dioxid, which may be formed in any suitable manner in the generator 12, and which may be conducted into the tank 11, by means of the pipe .13 provided with a valve 13.. I

The alkaline carbonate so formed is drawn off through the pipe 14, provided withthe valve 14, into the precipitating tank 15, where it is mixed with the soluble lead salt and converts the latter into lead carbonate.

The lead carbonate so formed settles upon the filter 16 at the bottom of the tank 15,

vwhile the filtrate, which is substantially the original electrolyte, is pumped by the pump 18 through the pipe 17 provided with the.

'valve 17 to the supply tank 1, and may be used over again. The lead carbonate formed in the tank 15 may be drawn off through the pipe 18, run through a filter press and pre pared for use. I

Instead of precipitating lead carbonate from the solution of lead nitrate or other solu-,

ble salt of lead which is discharged by the pipe 8 into the precipitating tank 15 by means of an alkaline carbonate, I may discharge the sodiumhydrate into the tank 15 4 and at the same time pass carbon dioxid ducing an oxidizing agent into the anode compartment. In the process herein described, this oxidizing agent consists of nitric acid which may be conveniently produced in the electrolyzing tank 20, by passing an electric current through the electrolyte supplied -.to said tank from the supply tank 1, by

means oi the pipe 23, provided with the valve I I Said tank 20 is provided withtwo foraminous diaphragms 2 1 andj21', and contains an anode 22 of carbon, and a cathode 22 of copper. Nitric acid is produced by the electrolytic decomposition of the'sodium nitrate with which the tank 20 ischarged, and is conveyed by the pipe 2 1, which is provided with the valve 24", into the anode compartment 3 of the tank 3. Sodiumhydrate is produced in the cathode compartment of the tank 20, and may be discharged through the pipe 25, provided with the valve 25, into the cathodecompartment of the electrolzyer 3. However other suitable oxidizing'agents may be used in place of the nitric acid above rcterred to.

By means of the direct process herein de scribed, I am enabled to produce white lead of a character that, for some purposes, is preferred to that produced by the indirect process set forth in the hereinbeiore mentioned Letters Patent. Thep'rocess is continuous,

and in addition to the lead and carbon dioxid consumed, requires only the addition from time to time of fresh quantities of the electrolyte.

I claim: I I 1 1. As an improvement in the art of producing white lead by electrolysis, the process herein described which consists in electrolytically separating an electrolyte intoa solvent of lead and an alkaline hydrate, dissolving metallic lead by said solvent thereof, electrolytical y producing an oxidizing agent and adding the same to'theresulting soluble salt of lead to prevent the formation of insoluble salts of lead, withdrawing said soluble salt of'lead, withdrawing and carbonating.

said alkaline hydrate, thereby producing an alkaline carbonate and then directly carbonating said soluble-salt of lead with said alkaline carbonate to produce white lead.

2. As an improvement in the art of pro-. ducing wlnte lead by electrolysis, the process herein described which consists in electro lyticallyseparatingan' electrolyte into a solvent of lead and an alkaline hydrate, producing by the action on lead of said solvent a solution of a soluble salt of lead, adding an 3',

oxidizing agent to said solution of said'psoluble salt oflead to prevent the formation of insoluble salts of lead, withdrawing said solution of said solublesalt of lead, witiulrawing and carbonating said alkaline hydrate and theieby producing an alkaline carbonate, and then dlrectly carbonatmg said solublesalt of lead with saidalkaline carbonate to produce white lead. I

In'testnnony whereof, I have hereunto subscribed my name-this fifth day of Jan.

EDWIN D'. CEL -APLIN. Witnesses:

' CHARLES" C.- Kun'rz,

G120. K. Wooowoa'rn.

iso- 

